Re: [boost] [hash] Extract module from functional + std::hash_combine

The C++11 std::hash was specified before boost::hash was created, so...

source : https://github.com/boostorg/functional/blob/develop/include/boost/functional... // Copyright 2005-2014 Daniel James. // Distributed under the Boost Software License, Version 1.0. (See accompanying // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) You're saying that the c++11 standard codified std::hash in 2005? This seems to me to be an extraordinary claim. More likely is that std::hash is the retarded cousin of boost::hash, and the c++11 committee's gravest error. On 19 December 2017 at 15:51, Daniel James via Boost wrote:

On 19 December 2017 at 14:12, Richard Hodges via Boost wrote:

...

Whoever decided to downgrade boost hash before solidifying its

uselessness

...

in the c++11 standard?

The C++11 std::hash was specified before boost::hash was created, so it wasn't downgraded. There have been several proposals for improving std::hash, some of which do have advantages over `boost::hash`, but the standards committee hasn't settled on any of them. But it's possible that the next standard will include 'hash_combine', as well as functions using variadic arguments:

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n3876.pdf

This is a bit of a compromise that makes it easier to implement custom hash functions but doesn't prevent any of the other proposal from going forward. I was thinking about implementing the variadic functions in that paper for 1.67.0, but I think I'll wait to see if it's added to the standard.

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